top,ps: improve /proc/PID/cmdinfo reading code

function                                             old     new   delta
display_status                                         -    1231   +1231
read_cmdline                                           -     101    +101
parse_conf                                          1284    1303     +19
arith                                               2033    2042      +9
collect_blk                                          467     474      +7
fsck_main                                           1909    1911      +2
dhcprelay_main                                      1125    1122      -3
singlemount                                         4555    4547      -8
read_close                                            50      36     -14
get_lcm                                              123     105     -18
ed_main                                             3111    3084     -27
func_args                                             73      28     -45
procps_scan                                          732     658     -74
top_main                                            2187     899   -1288
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 4/8 up/down: 1369/-1477)       Total: -108 bytes
   text    data     bss     dec     hex filename
 676048    2744   13968  692760   a9218 busybox_old
 675940    2744   13968  692652   a91ac busybox_unstripped

2 files changed, 37 insertions, 4 deletions

diff --git a/libbb/procps.c b/libbb/procps.c
index 8413ce8a1..1987e98fd 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -102,7 +102,7 @@ procps_status_t *alloc_procps_scan(int flags)
 void free_procps_scan(procps_status_t* sp)
 {
         closedir(sp->dir);
-        free(sp->cmd);
+        free(sp->argv0);
         USE_SELINUX(free(sp->context);)
         free(sp);
 }
@@ -266,6 +266,7 @@ procps_status_t *procps_scan(procps_status_t* sp, int flags)
 
                 }
 
+#if 0 /* PSSCAN_CMD is not used */
                 if (flags & (PSSCAN_CMD|PSSCAN_ARGV0)) {
                         if (sp->argv0) {
                                 free(sp->argv0);
@@ -292,10 +293,42 @@ procps_status_t *procps_scan(procps_status_t* sp, int flags)
                                 sp->cmd = xstrdup(buf);
                         }
                 }
+#else
+                if (flags & PSSCAN_ARGV0) {
+                        if (sp->argv0) {
+                                free(sp->argv0);
+                                sp->argv0 = NULL;
+                        }
+                        strcpy(filename_tail, "/cmdline");
+                        n = read_to_buf(filename, buf);
+                        if (n <= 0)
+                                break;
+                        if (flags & PSSCAN_ARGV0)
+                                sp->argv0 = xstrdup(buf);
+                }
+#endif
                 break;
         }
         return sp;
 }
+
+void read_cmdline(char *buf, int col, unsigned pid, const char *comm)
+{
+        ssize_t sz;
+        char filename[sizeof("/proc//cmdline") + sizeof(int)*3];
+
+        sprintf(filename, "/proc/%u/cmdline", pid);
+        sz = open_read_close(filename, buf, col);
+        if (sz > 0) {
+                buf[sz] = '\0';
+                while (--sz >= 0)
+                        if ((unsigned char)(buf[sz]) < ' ')
+                                buf[sz] = ' ';
+        } else {
+                snprintf(buf, col, "[%s]", comm);
+        }
+}
+
 /* from kernel:
         //             pid comm S ppid pgid sid tty_nr tty_pgrp flg
         sprintf(buffer,"%d (%s) %c %d  %d   %d  %d     %d       %lu %lu \
diff --git a/libbb/read.c b/libbb/read.c
index 05bf754e0..502d407c4 100644
--- a/libbb/read.c
+++ b/libbb/read.c
@@ -124,11 +124,11 @@ char *xmalloc_reads(int fd, char *buf)
 
 ssize_t read_close(int fd, void *buf, size_t size)
 {
-        int e;
+        /*int e;*/
         size = full_read(fd, buf, size);
-        e = errno;
+        /*e = errno;*/
         close(fd);
-        errno = e;
+        /*errno = e;*/
         return size;
 }